Mercury boiler



B. P. COULSON, JR

MERCURY BOILER 5 Sheets-Sheet 1 May 31, 1932.

Filed June 14, 1929 l:vllllvlulliilllillI!!! Inventor: Bevis F CoulsomJ aa His Attorneg.

May 31, 1932.

B. P. COULSON, JR

MERCURY BOILER Filed June 14. 1929 3 Sheets-Sheet 2 Inventor. I Bevis FcoulsomJrr, bg. M/ZZm/ His Atcor'neg.

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May 31, 1932. B. P. COULSON, JR

MERCURY BOILER Filed June 14, 1929 3 Sheets-Sheet 3 Fig. 7

Inventov. Bevis PCoulsonJw, bg I 04% His Attorneg.

Patented May 31, 1932 UNITED STATES PATENT OFFICE BIEVISv P. GQULSON, JR., OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, .A CORPORATION OF NEW YORK MERCURY BOILER Application filed June 14,

The present invention relates to mercury boilers, and especially to mercury boilers of the type disclosed in the application of W. L. R. Emmet and myself, Serial No.

306,486, filed September 17, 1928.

Owing to the fact that mercury is a relatively expensive liquid it is desirable that the quantity required in a mercury bo ler be reduced to the minimum, and one ObJQCt of my invention is to provide an improved construction and arrangement in a mercury boiler of the type disclosed in the above referred to application which requires but a relatively small amount of mercury for its operation. Also, it is important in a mercury boiler to maintain a sufliciently rapid circulation of the mercury to carry away the heat and maintain liquid mercury in contact with the surfaces from which heat is absorbed, and a further object of my invention is to provide an improved construction which accomplishes this result in a satisfactory manner.

Other objects and the advantages of my invention are pointed out in the following specification, and for a consideration of what I believe to be novel and my invention attention is directed to the following specification and the claims appended thereto.

In the drawings, Fig. 1 is a transverse sectional view of a mercury boiler construction embodying my invention; Fig. 2 is a vertical sectional view through one of the boiler tubes shown in Fig. 1, an intermediate portion of the tube being broken away; Fig. 3 is a sectional view taken on line 33 Fig. 2; Fig. 4 is a sectional view taken on line H Fig. 2; Fig. 5 is a top plan view of the filler blocks located in the interior of the boiler drum; Fig. 6 is a detail view of the filler blocks showing the manner in which they may be cut away at their upper ends; and Fig. 7 is a sectional view of the boiler structure shown in Fig. 1 mounted in a furnace.

Referring to the drawings l indicates a furnace in which the boiler is mounted. Any suitable fuel may be burned in it. In the present instance it is shown as being an 011 fired boiler, 2 indicating an oil burner and 3 1929. Serial No. 370,996.

through pipes 6 to a common header or drum 7 located at the forward end of the furnace. From header or drum 7 the elastic fluid is conveyed through pipes 8 to a second header or drum 9 located at the rear of the furnace. Connected to header or drum 9 is a conduit 10 through which the elastic fluid is conveyed to a point of consumption which may be, for example, an elastic fluid turbine. Only one of the boiler units is shown in the drawings,

but it will be understood that the several boiler units may be alike and are mounted side by side in spaced relation to each other. They may be supported in the furnace in any suitable manner. In the present instance they are shown as being suspended from I-beams 11 by means of tie rods 12.

Each boiler unit comprises a casing shown as a cylindrical drum 13 which is closed at its ends by suitable heads. Depending from the underside of drum 13 tubes 14, such tubes being flared slightly relatively to each other and being arranged directly over the firebox whereby the products of combustion pass vertically over them. Liquid mercury is supplied to the boiler drum by a conduit 13 which may lead from any suitable source of supply. 13 indicates the liquid level age for the boiler.

The boiler construction so far described is of the type disclosed in the above-mentioned application. My invention relates more particularly to an improved form of boiler tube 14: and to an improved arrangement of the tubes in the boiler drum.

According to my invention I make each tube a unit in itself in so far as the circulation of mercury is concerned, there being in each tube a continuous local circulation. By this arrangement, each tube in a way forms in itself an individual mercury boiler in are a number of boiler which the mercury circulates at high velocity, the drum serving to feed mercury to the respective tubes.

Each boiler tube comprises an outer tube in which is located a tubular core 16. Outer tube 15 is closed at its lower end, being provided with a rounded bottom and at its top it is fastened in an opening in drum 13 preferably by welding, as is indicated at 17.

Core 16 comprises a thick wall tube of the same general contour as the outer tube. It is held in spaced relation to the outer tube by suitable means such as a number of short longitudinally extending ribs 18 which may be formed by pressing outwardly some of the metal of the core. The lower end of the core terminates short of the bottom of the outer tube and is held in spaced relation to the bottom of the outer tube by one or more spacers or projections 19 (see Fig. 2) \Vith this arrangement, it will be seen that the pas sage thru the core, which passage is designated 20, communicates at its lower end with an annular passage 21 formed between the core and the inner surface of outer tube 1.5.

Core 16 may be formed with advantage from two spaced tubes welded together at their upper and lower ends, as is indicated at 22. The dead space between the tubes forming the core is preferably filled with air, although it may be filled with some other sub stance. The purpose of this is to provide an effective heat insulation between the passage through the inner tube or core and the outer tube to prevent the transfer of heat to the liquid while flowing down through passage 20. This is important in a mercury boiler. it being essential that a large quantity of relatively cool mercury be delivered continuously to the end of the tube which is exposed to heat radiation because mercury when not boiling is a much better heat remover than it is when boiling.

Core 16 terminates short of the upper end of outer tube 15 and located above it is a block 23, the lower end of which rests on the upper end of core 16. The outer surface of block 23 is spaced from the inner surface of tube 15 to provide an annular space which forms a continuation of passage 21. Block 23 is fastened from turning by a pin 24 which stands in a recess in the upper end of tube 15. Block 23 is provided with a central pas sage25 which is of greater diameter at its upper end than at its lower end. The lower end of the passage 25 communicates with a tube 26 which is fastened to block 23 and projects downward a suitable distance in passage 20 of the core. There is a slight clearance between the outer surface of tube 26 and the defining wall of passage 20. The outer surface of block 23 tapers inwardly from its lower end toward its upper end, as indicated by the dotted lines in Fig. 2, and is provided on its outer surface with ribs extension 15 is a head 28 provided with a central opening in which is located a tube 29 which projects downwardly to a point adjacent the lower end of block 23. Inside tube 29 is a second tube 30 which, throughout a portion of its length,.is spaced from tube 29 to form an annular feed passage 31. Tubes 29 and 30 and block 28 are shown as being supported by a thick plate 32 which rests in grooves 33 in block 27. The lower surface of block 28 is provided with an annular curved recess 34, and projecting through the block is a ring of tubes 35. the upper ends of which communicate with the space above block 28 through passages 36 of restricted area. With the above described arrangement it will be seen that there are provided two feed passages through which liquid is supplied to core passage 20, one feed passage being formed by tube 29, and the other by the annular space surrounding the tube 29.

Just above the inner surface of the boiler drum there is provided a feed tube 37 which communicates with the annular feed passage 31. Tube 37 serves to supply mercury from the boiler drum to the core passage 20.

In order to decrease the space inside the boiler drum there are provided filler blocks 38 which are of suitable size and which are spaced from each other and from the bottom wall of the boiler drum to provide spaces for holding the desired quantity of liquid mercury. In the under side of the blocks are recesses or chambers 39 into which the tube extension 15 project, and such chambers communicate with the vapor space of the boiler through passages 40 in the blocks. Where tubes occur between two blocks, the upper end of the tube is provided with a sealing cap 41 which is connected to the vapor space of the boiler by a tube 42 which extends through the corresponding passage 40 in the block. This special construction is required at these points in order that the upper end of the tube shall not communicate directly with the liquid spaces of the boiler. The tube extension 15 block 23, head 28 and tubes 29 and 30 form a structure which may be built as a unit and assembled at each boiler tube, and such units may be held in place by the filler blocks 38 which engage the upper ends of the units. The units are held from turning by the pins 24.

Blocks 38 are cut away as is indicated at 43 to provide a rectangular space into which mercury expelled from the tubes during op ill eration may accumulate.

In operation, liquid mercury is fed to the bottom of each tube through its core passage 20 and flows upward through annular passage 21. As it moves upward a part of it vaporizes and the vapor and entrained mercury, moving at comparative high velocity, impinge against the curved annular surface 34. Surface 34 serves to turn the stream and direct it downwardly, mercury particles falling into space through which they are fed to the down tube passage 20. The vapor escapes through pipes and restricted passages 36 to the vapor space of the boiler drum. It will thus be seen that the curved annular surface 34 forms a separator for separating the mercury from the vapor and directing the mercury back down to the bottom of the tube. There is thus set up a local circulation of the inercury in the tube. At the same time, mercury is fed continuously to the annular passage 31 through the feed pipe 37, the amount fed through pipe 37 being sufficient to keep the down tube passage 20 full of mercury. Any mercury particles that escape with the vapor through passages 36 will strike the dome above such passages and fall back into the upper end of tube 30. The tapered outer surface of block 23 serves to enlarge the area of the passage for the flow of vapor and mercury, this being desirable because the volume of flow increases as the mercury vaporizes.

The area of the restricted passages 36 is made of a size such that there is created a pressure in the upper part of chamber 25 a little greater than that opposite this point in tube 30. This difference in pressure is such that the level of mercury created in chamber 25 is well below the lower end of pipes 35 so that the vapor escaping up pipes 35 will not entrain any liquid mercury. The pressure of the vapor in the upper part of chamber 25 will be balanced by the level of mercury in tube 30, and preferably the arrangement is such that liquid mercury stands at about the upper end of tube 30. The tube 29 is made sufficiently long that under no operating conditions will the mercury level in chamber 25 surrounding tube 29 be lowered below the end of the tube, permitting mercury vapor to escape into the lower end of tube 29 and thus interfere with the flow of mercury to the passage 20. This is important because an uninterrupted flow of mercury to the lower end of the boiler tube must be maintained.

Pipe 30 is provided to guard against the vapor being forced down pipe 29 and through feed pipe 37 in case any sudden increase of pressure is created above block 28 due to the presence of liquid.

With the above described arrangement, it will be seen that when the boiler is o erating there is a continuous recirculation o the liquid mercury within each tube so that, in a way, each tube forms a boiler unit in itself, the tube being kept filled by mercury fed to it from the boiler drum. The path through which the liquid mercury circulates, since it is confined to the tube itself, becomes comparatively short so that I am enabled to provide liberal sized passages in the tube particularly at the top of the up passage between the core and the outer tube, and still reduce the quantity of mercury required for the boiler as a whole. tively short paths for the circulation of the mercury and increasing somewhat the size of the circulating passages, I increase the safety and reliability of the boiler while actually decreasing the total amount of mercury required. Also, the arrangement has the advantage that since the mercury for the tubes is drawn always from below the liquid level in the boiler drum, there is no danger of drawing dirt accumulated on the surface of the mercury down into the tubes.

IVhat I claim as new and desire to secure by Letters Patent of the United States, is:

1. In a mercury boiler, a boiler tube comprising an outer tube, a core located within and in spaced relation to the outer tube to provide an annular space for the up flow of mercury and vapor, said core having a down passage, the upper end of said down passage being larger in diameter than the remaining portion, a wall in the upper end of the outer tube, a tube which projects downwardly from said wall into said down passage, means providing a passage for feeding mercury from the side of the outer tube to the space within said last named tube, and means providing a passage of restricted area for the escape of vapor through said wall.

2. In a mercury boiler, a boiler tube comprising an outer tube, a core located within and in spaced relation to the outer tube to provide an annular space for the up flow of mercury and vapor, an end wall for the outer tube, a tube which projects down from said end wall into the core passage and defines there with an annular feed passage, said end wall having a curved surface which forms a separator and serves to direct liquid to said annular feed passage, and means providing a passage of restricted area through said end wall for the escape upward of vapor.

In witness whereof, I have hereunto set my hand this 13th day of June, 1929.

BEVIS P. COULSON, JR.

By providing compara- 1 

